PFI ES-3 clarification

[bryansonnier]

For "Alignment of facings or ends" it states that they "shall not deviate from the indicated position measured across any diameter more than 3/64" per foot or 1/32 whichever is greater."

My question is does this apply to the raised face section or the OD of the flange. For instance, the raised face diameter of a 2" CL1500 flange is 3.62" and the flange OD is 8.5". A 1/32" deviation based on the raised face is gives a tolerance of +/- 0.49 degrees but based on the flange OD is +/- 0.22 degrees. Both of these are very tight tolerances but the OD is extremely tight.

The image shows what looks like the flange OD but may be a flat faced flange as the facing of a raised face flange is the raised face i would assume.

 

[bryansonnier]

Is this the right category for this question? Should I try it in a different place like the "Welding Bonding Fastening" sub forum under "Structural Engineering"?

 

[LittleInch]

A bit more background would help like what's PFI ES-3?? A ref to it would be good.

Also no image.

But this is normally based on the flange face as that's what is important here to get the same as its mating flange face, from what I can gather.

It's also easier to get a straight edge to measure on a flange face.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[XL83NL]

PFI is also referenced under B31.3.

https://pfi-institute.org/products

Huub
- You never get what you expect, you only get what you inspect.

 

[LittleInch]

Never heard of it before, hence why a snapshot of the relevant page might be worth adding....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[XL83NL]

I was on mobile. Now on laptop. Here ya go

Huub
- You never get what you expect, you only get what you inspect.

 

[LittleInch]

The RF section.

"Facing" is pretty clear to me.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[1503-44]

You can apply the limit to any surface. The result is the same angle. The limiting angle (defined as a slope) is always going to be 1mm in 25cm. If Radius is not 25cm, say it's 10cm, the offset is limited to 1/25*10 = 0.4mm

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[bryansonnier]

Well actually (lol can't believe i said that), for the flanges that i deal with mostly, the 1mm on 25cm would be too tight, especially if we are talking about the raised face. Most of the flanges we deal with are 3" and under and most of those are 2". Most of the raised faces i have are well under a foot. But it does make a difference if you are measuring 1/32" on a 3.62" raised face (0.49° tolerance) or 1/32" on a 8.5" flange OD (0.21° tolerance). I get they are shooting for a 0.22°-0.23°tolerance but there seems to be some bonus tolerance for smaller flanges.

I know it said "facing" but the image didn't show any raised face and some flanges are flat faced so i was a little unsure. I know it was built for taking measurements in the field, but below 1 foot the tolerance is not consistent. Going down from half a degree to one fifth of a degree. Also 0.2 degree's is seams fairly tight considering how much welding can case the part to pull one way or the other.
1mm/25cm = 0.23°, 3/64in / 1ft = 0.22°. I was unaware that welders were expected to be accurate to within 2 tenths of a degree. I'm glad they are that good, i know i wouldn't be.

 

[LittleInch]

I get the point and most workmanship specification I see use angles rather than dimensions.

The guidelines are exactly that - guidelines - and probably not written with lines less than 6" OD in mind. So go back to an angle and forget the 1mm thing

The issue for me is simply what is practical to do. SO set up your pipe exactly horizontal - easy just rest a spirit level on it.
The vertical flange face - easy - just rest your vertical spirit level against whatever the mating surface is. If its RF then its the RF surface., if its a FF flange then its the entire flange. For an RF flange its difficult to measure the verticality of something the spirit level isn't touching....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.